Composition for lessening malodors during hair treatment and hair removal and method of use

ABSTRACT

The use of strontium ions to reduce malodors associated with various chemical hair removal and hair treatment procedures is disclosed. Typical formulations include alkali metal thioglycolate depilatories containing from 0.2% to 2% strontium chloride.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority based on a U.S. Provisional PatentApplication filed Jul. 2, 2002, titled “Composition For Lessening,Eliminating or Preventing Malodors and Method of Use”.

FIELD OF THE INVENTION

This invention is directed to the use of strontium ions to lessen oreliminate malodors due to sulfides during certain hair treatment andhair removal procedures. Such malodors may be formed, for example, whenS—S bonds are broken in connection with hair depilation. The inventionis, however, useful in connection with the minimization of sulfide odorsarising from other sources and processes.

BACKGROUND OF THE INVENTION

The removal of hair from the human body has received considerableattention. The hair and hair follicles can be removed by certainsurgical operations or by electrolysis. Also, it is customary to removehair by the use of tweezers or other instruments but does not have thesame long lasting effects as surgical procedures. Moreover, the use ofhair removal instruments is generally confined to removal of hair from alocalized area, such as, along the eyebrows or nostrils.

Creams or cold waxes have been formulated in the past for the purpose ofhair removal to the end of achieving more lasting effects as well as theability to apply over greater areas than is possible by plucking outindividual hairs from a localized part of the body. For example, it hasbeen proposed in the past to employ a combination of honey, rosin andwax which are heated together and thereafter combined with citric acid,which is mixed into the composition until it has acquired a creamytexture, reference being made to U.S. Pat. No. 2,091,313 to W. M. GrantGrant fails to state to what temperature level the formulation isheated.

British Letters Patent No. 901,624 to E. Wenden discloses theformulation of a cream made up of sugar and lemon juice, glycerine,boric acid powder, sodium chloride and a water carrier. Theseingredients are heated, then allowed to cool to a temperature at whichthey may be poured into separate jars or containers, and specificallyare heated to a temperature on the order of 278° F. to form a plasticmass. The resultant composition is applied to the skin so as to becomematted with the hair, then immediately stripped from the skin to causeremoval of the hair with the plastic mass.

Other methods of hair removal have employed naturally occurring chemicalsubstances, such as certain plant extracts, which have the ability tocause the removal of human body hair when applied to a particular skinsurface. Some of these naturally occurring chemical depilatories may beare quite harsh, causing substantial irritation to human skin,particularly to sensitive skin areas such as the face, and arefrequently malodorous as well.

In conjunction with waxes of various sorts, the most widelyused presentday depilatory agents are probably creams and ointments which contain astheir active ingredient disulfide bond breakers such as salts ofmercaptan acids, particularly alkali metal and alkali earth metal saltsof thioglycolic acid. These sales attack the most recently formedportion of the hair shaft, that is, the part closest to the skinsurface. They act by rupturing the disulfide bonds in the keratinprotein found in the hair shaft, weakening the hair and causing it to beruptured at the surface of the skin, an effect somewhat similar toclosely shaving the skin area. The hair root, however, remains in thefollicle and the disulfide bond breaking salts have a deleterious effecton the skin and give rise to unpleasant odors. One aspect of the presentinvention involves the reduction of these unpleasant odors.

SUMMARY OF THE INVENTION

1. Objects of the Invention.

It is an object of the present invention to provide compositions for usein the removal of human hair that are safe, effective, non-irritatingand non-toxic and that can be utilized in simple and inexpensivehair-removal methods. It is a further object of the invention tochemically remove human hair in a manner with less associated malodorsthan has heretofore been accomplished. There and other objects of theinvention will become apparent from the description set forth herein.

2. Brief Description of the Invention.

Deodorization of Depilatories and Hair Bleaches.

This invention provides for a means of deodorizing hair treatment andhair removal processes. More particularly this invention covers means ofpreventing formulations containing compounds with mercaptan moietiesfrom becoming odiferous during the course of hair treatment and hairremoval. More particularly this invention covers methods of deodorizingdepilatories, hair permanents and hair straighteners. It also covers theprevention of odor development when such products are applied to hairand skin and areas being depilated.

As described above, many commercial depilatories utilize alkali metaland alkali earth metal thioglycolates as reducing agents to weaken hairfor the purposes of depilation. When formulated into depilatoryproducts, thioglycolates tend to decompose over time releasing hydrogensulfide gas, which has an unpleasant odor similar to “bad eggs”.Additionally, the reactions of depilatories with hair produce hydrogensulfide and methyl mercaptan, thereby creating malodors duringdepilation. Similarly products designed to permanently or temporarilyweaken hair such as permanents and products react with thesulfur-containing amino acids in hair and generate odiferous sulfides.

Copper and lead are known to react with sulfides producing insolublenon-volatile compounds. However, both copper and lead are toxic andproduce dark colored products when reacted with sulfides, making themunsuitable for use in personal care products. Copper and possibly leadalso react with mercaptans making them potentially incompatible withthioglycolates. Silver blackens and precipitates as silver hydroxidefrom alkaline solutions. It also darkens the skin making it unsuitablefor use in personal care products. Silver also strongly reacts with mostsulfur-containing compounds, making it incompatible with thioglycolates.

The present invention is directed to formulations containingthioglycolates together with sources of strontium ions atconcentrations, which reduce or eliminate the generation of sulfideodors from the formulation. It also is directed to depilatories, permsand hair straighteners containing sources of strontium ions to preventthe development of sulfur-containing malodors when the products arecontacted with hair.

Depilatory formulations containing thioglycolates generate sulfide odorson aging. We have now found that when a source of strontium is added tosuch depilatories, the development of sulfide odors on aging issignificantly reduced or eliminated. Additionally, when applied to theskin for the purposes of removing hair, sulfide odors are not generatedand the skin remains odor-free. Furthermore, formulations containingsources of strontium ions were not found to adversely affect theefficacy of the depilatory formulation. While not being bound by anyparticular theory of operation, we hypothesize that strontium ions reactwith any free sulfide ion to produce insoluble strontium sulfide andthereby prevents the formation of hydrogen sulfide and hence the releaseof malodor.

Any source of strontium ions is effective for incorporation in theformulation. However, soluble non-toxic compounds such as strontiumacetates and chlorides are preferred. The level of strontium compoundused should be sufficient to provide enough strontium ions to preventthe development of sulfide odor, for example from about 0.05 to 8%, morepreferable from 0.1 to 4%, most preferably 0.2 to 2%, wherein allpercentages are by weight of the respective metal ions.

The following is an example of a hair depilatory agent preparedaccording to the instant invention.

EXAMPLES

Example 1 Control A Control B Water 64.0 64.0 64.0 Potassiumthioglycolate 11.5 11.5 11.5 Calcium hydroxide 5.0 5.0 5.0 Cetearylalcohol 4.5 4.5 4.5 Light mineral oil 8.0 8.0 8.0 Sodium hydroxide 1.51.5 1.5 Urea 5.0 5.0 5.0 Strontium chloride 0.5 0.0 0.0 Zinc oxide 0.00.5 0.0 100.0 100.0 99.5

The products stored for two months at room temperature and the odor ofthe product in the container was evaluated. Example 1 and Control A wereessentially odor-free. The Control B had quite a perceptible unpleasantodor.

The three products were then applied to areas of the skin fordepilation. Example 1 and Control B were both effective in removing thehair. Control B was significantly less effective in removing hair. Onthe other hand Example 1 and Control A did not produce an odor whereasControl B did. Also the treated skin after use of Example 1 and ControlA was odor free whereas the skin treated with Control B had anunpleasant odor.

This demonstrates that strontium ions effectively prevent odordevelopment from the depilatory formulations without adversely affectingdepilation performance. In contrast, while zinc ions do prevent odor,they also interfere with depilation performance.

FURTHER EXAMPLES

A hair removal product for men having the below listed composition,stability and viscosity was prepared according the following procedure.Ingredient Wt % Dionized water 73.475 Calcium Thioglycolate 6.000Calcium Hydroxide, powder 2.500 Sodium Hydroxide, bead 1.000 CetearylAlcohol and Ceteareth-20 8.000 (a.k.a. Promulgen D) Light Mineral Oil7.000 Chromium Hydroxide Green 0.025 Perfume 0.500 Sunflower Oil 0.500Camelia Oleifera Extract 0.500 Strontium Chloride 0.500 Total 100.000Procedure:

1. While stirring heat de-ionized water and add calcium thioglycolate.

2. When the temperature reaches about 55 °C., add calcium hydroxide.

3. When the temperature of the mixture reaches about 65 °C., slowly addthe sodium hydroxide.

4. When the temperature reaches 75 °C., add the Promulgen D. Then addLight Mineral Oil, Chromium Hydroxide Green, Sunflower Oil, and CameliaExtract and stir for a further 5 minutes)

5. Remove heat while continuing to stir.

A similar control product was also prepared without strontium chloride.A sample of the product containing strontium chloride is placed onstability test with the control product, not containing strontiumchloride. After 3 months at 100° F. the test product has a pleasantfragrance, while the control product, not containing strontium chloride,has an unpleasant off-odor similar to bad eggs.

Fresh product containing strontium chloride is applied to the legs,chest and back of male subjects. It is allowed to remain in contact withthe hair for 8 minutes. The product is then wiped off the skin and thehair is effectively removed. The skin remains essentially odor free. Thecontrol product not containing strontium chloride is also found to beeffective in removing hair. However, an unpleasant lingering odor isimparted to the skin.

A hair removal product for women having the below listed composition,stability and viscosity was prepared according to the followingprocedure. Ingredient Wt % Dionized water 63.435 Potassium Thioglycolate11.500 Calcium Hydroxide 5.000 Urea 5.000 Sodium Hydroxide 1.500Cetearyl Alcohol and Ceteareth-20 4.500 (a.k.a. Promulgen D) LightMineral Oil 8.000 D&C Yellow #8 0.005 Chromium Hydroxide Green 0.060Perfume Compound CH15736 0.500 Strontium Chloride 0.500 Total 100.000Procedure:

1. While stirring heat de-ionized water and add potassium thioglycolate.

2. When the temperature reaches approximately 55 °C., add calciumhydroxide.

3. When the temperature of the batch reaches 65 °C., slowly add the ureafollowed by the sodium hydroxide.

4. When the temperature reaches 75 °C., add the Promulgen D followed bythe light mineral oil, yellow dye and chromium hydroxide green and stirfor 5 minutes.

5. Remove heat and allow to cool.

6. When the temperature drops to 56 °C., add the perfume and stir for 1minute.

7. Homogenize the batch for 1 minute.

8. Mix and cool to ˜40 °C.

9. Add the strontium chloride and mix for a further 5 minutes untilcontents cool to 30 °C.

A similar control product not containing strontium chloride was perparedusing the same procedure.

A sample of the Example product containing strontium chloride is placedon stability test with the control product, not containing strontiumchloride. After 3 months at 100° F. the test product has a pleasantfragrance, while the control product, not containing strontium chloride,has an unpleasant off-odor similar to bad eggs.

Fresh product is applied to the legs of female subjects and left incontact with the hair for 4 minutes. The product is wiped off the skin.The hair iseffectively removed while leaving the skin essentiallyodor-free. When a control product, not containing strontium chloride, isapplied to the legs it is also effective in removing the hair. However,there is a perceptible unpleasant odor which lingers on the skin.

1. A chemical depilatory composition comprising at least one chemicaldepilatory component and an effective sulfide malodor lessening,eliminating or preventing amount of strontium ions.
 2. The compositionof claim 1 wherein the chemical depilatory is selected from the groupconsisting of alkali or alkali earth thioglycolates.
 3. The compositionof claim 1 wherein the said strontium ions are present in the form of asoluble, non-toxic strontium salt in an amount ranging from about 0.2%by weight of said salt up to about 2% by weight of said salt.
 4. Thecomposition of claim 3 wherein said chemical depilatory component isselected from the group comprising potassium thioglycolate, calciumthioglycolate and mixtures thereof and said strontium compound isstrontium chloride.
 5. A method for removing hair from the surface ofhuman skin comprising applying to the surface of said skin thecomposition of claim 1.